This invention relates to a temperature indicator incorporated into a wheel hub to generate a warning signal when wheel end component temperatures exceed a predetermined limit.
Wheel separation occurs when a wheel end assembly component becomes separated from the associated axle. A wheel end assembly includes a wheel hub that is rotatably supported on a spindle with bearings. Many wheel separation incidents involve disintegration of the wheel bearings and/or spindles.
Typically, these separations occur as a result of improper maintenance, such as inadequate lubrication or incorrect bearing adjustment, for example. This causes the bearings and spindle to experience elevated temperatures. During extended vehicle operation, these temperatures can approach the melting point of the wheel end components, which will eventually cause wheel separation.
Vehicle operators have indicated that it is difficult to determine whether the wheel end components are operating at elevated temperatures. Often, wheel separation can occur with no warning to the operator.
Thus, it is desirable to have a way to provide the operators with an indication of when the wheel end components are experiencing temperatures that exceed the normal operating range. The indicating method and apparatus should be cost effective, easily incorporated into the wheel end, and should provide an accurate indication of when components are operating at elevated temperatures.
A temperature indicator is mounted within a wheel hub to generate a warning signal when wheel end components exceed a predetermined temperature. Preferably, the temperature indicator is comprised of a thermal battery that is activated only when the wheel end components exceed the predetermined temperature. Once activated, the battery powers an RF transmitter to generate a wireless warning signal that is transmitted to a remote receiver to display a warning.
In an alternate embodiment, the temperature indicator includes a first electrolyte and a second electrolyte separated by a metal alloy. The alloy has a predetermined melting point that generally corresponds to the predetermined temperature. When the temperature of the wheel end component exceeds the predetermined temperature the metal alloy melts to permit interaction between the first and second electrolytes to generate the warning signal.
The preferred inventive method for generating a warning to indicate overheated wheel end components includes the following steps. The temperature indicator is mounted adjacent to a bearing in a vehicle wheel assembly. The temperature indicator is activated only when wheel end component temperature exceeds a predetermined temperature and the warning signal is generated when the temperature indicator is activated.
The subject method and apparatus provides a simple and effective way to indicate when a wheel end component temperature has reached an undesirable limit. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.